Telephone-exchange system



. APril 7, 1931- R. L. STOKELY 1,799,654

TELEPHONE EXCHANGE SYSTEM Filed Jun 28. 1929 4 Sheets- Sheet 1 noun noun nuun UDQUUU DUB POLARIZED POI-HRIZED poLARlzED ATTORNEY April 7,1931. R. L. S TQKELY 1,799,654

TELEPHQNE EXCHANGE SYSTEM Filed June 28, 1929 {sheets-sheet 2 fie. E.

A 7 TURNEY April 7,193 R. L. STOKELY 1,799,654 TELEPHONE EXCHANGE SYSTEM Filed June 28, 1929 4 Sheets-Sheet 3 /N VE N TOR- R. L. Bram-1) A T TURNE) April 7, 1931. R. L. STOKELY I TELEPHONE EXCHANGE SYSTEM 4 Sheets-Sheet 4 Filed June 28, 1929 Y m m m r T WW In m Em mm M M Q PM nan Q v Q. I l1 4 H H =9 f I. R Q mg 3% L. v Q L Hv 11... J =.v ll w U Nv R Q hs 4H wmmm E Q m I n- N/I II Hl a 5 m5 Flu Q As QM Q F N m9 \M v 8N w N Q II I. u Q rlln v t gm w ATTORNEY Patented Apr. 7, 1931 Unites STTE I PATENT" or FICE.

RAY L. STOKELY, or rLonAL PARK, NEW YORK, Assrcnon TO BELLTELE-PI-IONE LABORATORIES, Inconrone'rnn, or new YonK, n. Y., a CORPORATION or nEw YORK Application filed June 28,

repeating means in each of the trunks used in connecting calling lines to idle selectors. According to this invention a polarlzed relay is locatedat each station of a party line to enable the identification of the calling station by testing means assoclated with the trunk used in extending the line to an idle selector. The testing means are connected to the line, before the calling subscriber begins dialing, to partially identify the calling station, are connected to the line a second time as soon as the first digit of the called number has been dialedby the calling subscriber to check the previous partial identification, and are again connected to the .line as soon as the second digit of the called number has been dialed to complete the identification of the calling line.

According to this invention means are provided whereby the dialing of asecond digit is simulated, in case the number-of the called station is composed of only one digit, so that the calling station can be completely identified by the third test'of' the line.

According to another feature of this invcntion means are provided for reversing the direction of current fiow over the calling subscribers line, if the identifying ground connection is closed at the calling station, so

n as to free the line from this ground connectlon before dialing begins and thereby obviate the necessity of including pulse repeatmg means in the trunk used inextendlng the hue to a selector circuit. In case the cur- 47 rent flow over the calling line after the called subscriber or operator has answered, is in such adirection as to cause the identifying ground to be again connected to the line, the line is again reversed with respect to the CO talking battery supplysoas to free the line TELEPHONE-EXCHANGE SYSTEM 1929. Serial No. 374,320.

ground connection during, conversascribers message register, to make certain that the apparentanswer of the called subscriber is not caused by other temporary'rconditions, is common to a group of trunks used in extending calling lines to idleselectors.

A system in which this invention is embodied is shown diagrammatically in the drawing which comprises five figures. Fig. 1 shows a line-finder circuit LF and four subscribers stations, designated W, J, M

andR, respectively, connected by a common line to terminals inthe bank of the line- 'finder switch. Fig. 2 shows a trunk circuit T which is individual to the line-finder circuit LF. Fig. 3 shows a register control circuit RC which'is commonto a plurality of trunks, suchas T. Fig. a'shows a 'selec tor circuit S, a connector circuit. C, asubscribers station D, a trunk circuit OT, and a cord circuit at an operators position 0. The line-finder, selector and connector switches are of the well-known Strowger type, but the invention may be appliedto systems using other typesof, switches. Fig. 5 shows how Figs. 1 to 4, inclusive, should :be arranged.

Each of the substations W, Jfld andR are arranged to close an identifying ground connection, when a call is originated'thereat, as controlled by a polarized relay whichis in series with the line. A retard coil is in cluded in the identifying ground connection so as to minimize the effect of this ground during conversation in case the called station is on the same line as the calling station, the retard coil being connected between two rc sistances which are bridged in series across thewinding of the polarized relay. Each station is also equipped with a dial for controlling the operatlon of the switches used in extending a connection to the called station. The polarized relaysQl and 31, at stations J and M, are so connected as to operate in series with the windings of the line "relay 2when the receiver is removed from the receiver hook to originate a call. The polarized relays 11 and 41, at stations W and R are so connected as to remain normal when connected in series with the windings of relay 2 and to operate when the current over the line is reversed. At stations and J the operation of the polarized relay closes the identifying ground connection while at Stu tions M and R the identifying ground connection is normally closed and the operation of these relays opens this connection.

The line-finder switch is equipped with two banks and two sets of brushes similar to the switch disclosed in United States Patent 1,567,240 issued to Carpenter on December 29, 1925, but the associated circuit is somewhat different from that shown in the patent to Carpenter. Upon the origination of a call at any one of stations W, J, M and R of line 1, the line-finder LF (or, if this line-finder is busy, some other line-finder to whose terminal bank the line 1 is multip'led) is effective to advance one of its sets of brushes into contact with the terminals to which this line is connected. The calling line is thereupon extended to the trunk circuit T this trunk circuit serving to connect the line-finder rith its associated selector circuit S.

The trunk circuit T is arranged to make three tests of the calling line. The first of these tests takes place as soon as the calling line is extended through the linerfinder to the trunk T, the two windings of test relay 83 being connected to the tip and ring conductors, respectively, of the calling line. One of the windings of relay 83 is connected to the negative pole of the 48 volt central 0ffice battery, while the other is connected to the negative pole of the special volt test battery- The windings of this relay oppose each other when a metallic line loop is connected thereto so as to prevent its operation but when a grounded line loop is connected across its windings, the relay operates. The current over the line during the first test maintains the polarized relay at the calling station in the same condition, normal or operated, as when the windings of line relay 2 were connected to the line. Thus if the call originated at stationlVpolarized relay 11 is normal, the line is not connected to ground, 2

and test relay 83 does not operate; it the call originated at station J polarized relay 21 is operated, the line is connected to gro-un d, and test relay 83' operates; if the call originated at station M polarized relay 31 is open ated, the line is not connected to ground, and test relay 83 does not operate; and if the call originated at station R polarized relay 41 is not operated, the line is connected to ground, and test relay 83 operates. If testrelay 83 operates on the first test it closes a circuit for operating the auxiliary relay 89. If operated, the auxiliary relay 89 reverses the line conductors with respect to line relay of the selector S so that the polarized relay at the calling station (either J or R) will release or operate to open the identifying ground connection and thereby render the dialing circuitsmore effective in controlling the selector After the first dig-it has been dialed the windings of relay 83 are again connected to the conductors of the calling line for a second test; but the winding formerly c011- nected to the tip conductor is now connected to the ring conductor and the winding formerly connected to the ring conductor is now connected to the tip conductor. Thus if the call originated at station W polarized relay 11 is operated, the line is connected to ground, and testrelay 83 operates ifthe call originated at station J polarized relay 21 is not operated, the line is not connect-ed to ground, and test relay 83 does not operate; if the call originated at station M polarized relay 31 is not operated, the line is connected to ground, and test relay 83 operates; and if the call originated at station E polarized relay 41 is operated, the line is not connected to ground, and test relay 83 does not operate. If test relay 83 operates during the second test it closes a circuit for operating a second auxiliary relay. The second test is, therefore, effective to check the results of the first test and the operation of test relay 83 on both the first and second tests of the line indicates that some ground other than the proper identifying ground is connected to the line and is preventing the identification of the calling station.

After the second digit of the called number has been dialed, or, if the called number consists-of only one digit as is often the case on callsto an operator, after the dialing of a second digit has been simulated, a third test is made by connecting the windings of test relay 84 to the tip and ring conductors respectively of the calling line, Since the windings of relay 84 are connected to battery in parallel, there is no current through the winding of the polarized relay at the calling station; and relay 84 is operated only if the call originated at station M or at station It, at either of which the line is connected to ground when the polarized relay is normal. If test relay 84 operates it closes a circuit for operating a third auxiliary relay. Thethird test is, therefore, effective in combination with the first test to completely identify the calling station; and the operation or nonoperation of the above mentioned auxiliary relays selects, and partially closes a circuit for operating that one of the four register control relays 117, 119, 121 and 123 which corresponds to the calling station.

The selector switch S is represented by brushes 153, 154 and 155 and by the terminals with which these brushes are shown to be in contact. The connector switch C is represented by brushes 159, and 161 and 'by the terminals with'which they are shown leading to their brushes. For a detailed dejack at which this trunk terminates.

scription of the operation of these switches reference may be had to pages 57 to 65 inc1usive of the second edition of Automatic Telephony by Smith and Campbell.

The trunk circuit OT which leads to the operators position at O is connected to termina ls in the bank of the selector S so that a calling line may be extended thereto by the dialing of only one digit. The'trunk is arranged to temporarily open the connection from the calling line when the operator inserts the. plug of the answering cord in the This temporary opening of the circuit which includes the calling line simulates the dialing ot a second digit and renders the trunk circuit Teflective to make the aforementioned third test of the calling line and thereby complete the identification of the calling station.

The register control circuit is arranged to control the operation of the message registers of the stations of all of the lines to which this control circuit'is common-that is, of all of the lines which terminate in the banks of the line-finders associated with the trunks to which the control circuit RC is common. Conductor 130 leads from the winding 01 relay 131 of the control circuit to relay 93 of trunk T, thence over conductor 106 to the corresponding relay of the next trunk and so on to'each of the trunks with which the control circuit is operated; The control relays 117, 119, 121 and 123 each controls one or more auxiliary relays of the multi-contact type; and the auxiliary relay or relays, associated with each of the control relays, in turn control the message registers of all of the stations of like designation. Thus control relay "117 and the auxiliary relay 118 control the message registers of the W stations, control relay 119 and auxiliary relay 120 control the message registers of the J stations,'control 'relay 121 and auxiliary relay 122 control the message registers of the M stations, and control relay 123 and auxiliary relay 12a control the message registers of the R- stations.

When a connection (for which the calling subscriber should becharged) 'is established,

the usual reversal of the current over the calling subscribers line is effective to operate thepolarized supervisory relay 91 in the trunk T. With relay 91 and its auxiliary relay 92 operated, the register control circuit RC (if not in use with some of the. trunks to'which it is common) is effective to delay the operation of the message register of the calling station for an interval of from two to four seconds. This 'delayis intr0- duced to prevent the operation of the calling subscribers message register in case relay 91 is momentarily operated. The interrupter 133 and the counting relays 134C and 135 measure thisinterval and upon its expiration the previously selected control relays are operated to connect the windings of the register of the calling 7 station; to the boost'er-battery 142; These operationsare best explained by a detailed description of the operation of the circuits shown in the drawing.

Assume that a call is originated at one-of stations WV, J, M and R, that station D is the called station and that the call is one for which the calling station should be charged. When the receiver is removed from the receiver hook at the calling station, line relay 2 operates 1n an obvious circuit over line 1. The current over] the line is in such a direction thatpolarized relay 21 operates if the call originated at station J or polarized 'mon to all of the lines in the group with line 1. In operating, relay 5 connects ground to starting conductor 6 and also connects ground over conductor 7 to the commutator segment, ot' all of theline-findershaving access to line 1, which corresponds to the level in which the terminals of line l are located.

Conductor 7 is shown connected to the fourth commutator segment'o'f the line-finder LF, and line'l is, therefore, assumed-to be con nected to terminals in-the fourth level of its winding, inner upper back contact of re lay 53, over conductor 6, to ground at relay 5. In operating, relay 50 connects ground to the sleeve conductor 7301f the trunk T and closes a circuit from ground at its outer lower front contact, over conductor 75 of trunk T, through the inner back contact of relay 79 to the lefthand winding of test control relay 81. Relay 81 operates thereby preparing the trunk circuit for the first identlfication test of the calling line: Relay 50 also closes a circuit from. ground through its I inner lower front contact, over conductor 59, back contact of the vertical stepping'magnet 56, back contact of the rotary stepping magnet 57 upper winding of stepping relay 52, and through the outer lower back contact of relay 53,"to battery'i The stepping relay 52 operates thereby closing a circuit from the ground at relay 50 over conductor 59, through the front contact ofrelay 52,

inner lower back contact of relay 54, winding of the vertical stepping magnet 56, and through the lower back contact of relay 53, to battery. The vertical magnet 56 operates thereby stepping the shaft and brushes 61 to 66 inclusive up to the level of the first group of line terminals. The vertical olfnormal springs VON are actuated as soon as the shaft is moved out of its normal position, ground being thereby connected through the lower front, contact of these springs to conductor 60. In operating, magnet 56 opens the circuit through the winding of stepping relay 52. The commutator brush 67 is now in contact with the segment of the commutator which corresponds to the group of lines which are connected to terminals in the first level of the multiple bank. Brush 67 is connected through the upper winding of relay 54, back contact. of rotary stepping magnet 57, upper winding of stepping relay 52, and through the lower back contact of relay 53, to battery; but the stepping relay 52 releases when magnet 56 opcrates since the upper windings of relays 52 and 54 are not energized until the brush 67 makes contact with the fourth commutator segment (to which ground was connected by the operation of group relay Inreleasing, relay 52 opens the circuit through the winding of the vertical magnet; and the release of the vertical magnet again closes the operating circuit through the lower winding of relay 52. The stepping relay 52 and vertical magnet 56 alternately operate and release to move the line-finder shaft up stepby-step until the commutator brush 67 makes c ontactwith the segment (in this case the fourth segment) which corresponds to the level in which the terminals, to which the calling line connects, are located.

\Vhcn brush 67 makes contact with the fourth segment, relay 54 operates and relay 52 is, held operated in the circuit through their upper windings. Relay 54 locks in a circuit from battery through the lower back contact of relay 5.3, winding of vertical magnet 56, lowerwinding and outer lower front a contact of relay 54, and over conductor 59 to ground at relay this circuit is not eflective to hold magnet 56 operated. In operating, relay 54 opens the operating circuit through the winding of the vertical stepping magnet 56 and closes a circuit from battery through the winding of the rotary stepping magnet 57, inner lower front contact of relay 54, front contact of relay 52, over conductor 59, to ground at relay 50, Magnet 56 releases and magnet 57 operates In operating, magnet 57 opens the circuit through the upper windings of relays 52 and 54 and advances the two sets-of multiple brushes (61 to 63 inclusiveand' 64 to 66 inclusive) into contact with the first two sets of terminals in the selected level of the line-finder bank. Relay 54 is slow in operating so that the brushes will not be vibrating when they enter the banks. If the calling line is not connected to either of the first two sets of terminals relay 52 releases when the circuit through its upper winding isopened. In releasing, relay 52 opens the circuit through the winding of rotary magnet 57 and the release of magnet 57 again closes the circuit through the upper winding of relay 52. The stepping relay 52 and rotary magnet 57 are, therefore, alternately operated and released to advance the line-finder brushes step-byat relay 50; the cut-off relay 3 operates and relay is suiiiciently energized to close its inner lower front contact. The lower winding of relay 55 is thereby energized in a circuit from battery through this winding and locking contact, over conductor 69, through the front contact of magnet 57 and over conductor 73 to ground at the upper contact of relay 50, Relay 55, which is completely operated in the circuit through its lower winding, extends the connection from brushes 61 and 62 to the trunk conductors 71 and 72.

If and when brush 66 makes contact with the sleeve terminal of the calling line, a circuit is closed from battery through the Winding of the cut-off relay 3, upper front contact of relay 2, conductor 4, brush 66, lower winding of relay 51, inner upper back contact of relay 55, lower back contact of relay 51, lower winding of relay 52, and over conductor 59 to ground at relay 50; the cutoff relay 3 operates, relay 52 is held operated, and relay 51 is sufficiently energized to close its inner upper front contact. The upper winding of relay 51 is then energized in a circuit from battery through this winding and locking contact, through the inner upper front contact of relay 54, conductor 69, front contact of magnet 57, and overconductor 73 to ground at relay 50. Relay 51, which is completely operated in the circuit through its upper winding, closes a circuit for operating relay 55; this circuit may be traced from battery through the lower winding of relay 55, inner lower front contact of relay 51, middle lower front contact of relay 50, and over conductor to ground at the VON. springs. -With relays 51 and 55 both operated the connection from brushes 64 and is extended to the trunk conductors 71 and 72. The circuits for completely operating andlocking relays 51 and 55 are opened each plete operation of relay 55 is effective to short.

circuit its upper winding and if brush 66 finds the calling line the complete operation of relay 51 is effective to short vcircuit its lower winding so that in either case the cut off relay 3 is held operated over conductor 68', in series with the lower winding of relay 52,

thence over conductor 59 to ground at relay 50. The complete operation of relay 55 is, in either case, also effective to open the circuit through the lower winding 'of relay 51, to close a circuit for operating relay 53, and to i connect ground through the outer lower front contact of relay 50 and the outer upper front contact of. relay 55 to the trunk conductor 74. The circuit for operating relay 53may he traced from battery through its lowerwinding, through the outer lower'front contact of relay 55, and over conductor 60 to ground at the VON springs. In operating I relay 53 disconnects the upper winding of relay 55 from conductor 68 and connects this conductor, through the outer upper front contact of relay 53, over sleeve conductor 73, to ground at relay 50 thereby holding the cut-off relay 3 operated but short circuiting the lower winding and causin the release of relay 52. The release of relay 52 opens the circuit through the winding of the rotary magnet; In oper ating, relay 53 also connects conductor 68 through its outer'upper, front Contact to conductor 73 in parallel with. the front contact of the rotary magnet 57 so that relay 55 and relay 51 if operated, do not release when magnet 57 releases. In operating, relay 53 opens the circuit through the lower winding of relay 54so that relay 54 releases. The release of relay 54 disconnects the locking winding of-relay 51 if operated, from conductor 69 and connects this winding over con- (luctor 69 to ground at the VUN springs. In

the remainder of-this description it is as;

sumed that brushes 61 to l 63 are in contact with the terminals of the calling line and that relay 51 is not operated. r

, In operating, relay 53 is also effective to close a circuit from battery through its upper winding and front contact to thestarting conductor 6 and to extendtlns conductor through its inner front contact, over conductor 70, to the next line-finder in the same group with the line-finder LF. Relay 53 also disconnects the winding of relay '50. from starting conductor 6. Relay 50 is slow in re leasing so that the ground at its upper front contact is not disconnected from "sleei' e-eon? ductor 73 until after groundhas been connected'to this conductor by the operation of relay 94, as is hereinafter described. Relay 50, in releasing, disconnect-s ground from I conductors 74 and 75, and connects its middle lower back contact in parallel with the outer lower front contact of relay 55, thus rendering the circuit through the lower winding of relay 53 independent of the continued operation of relay 55.

The aforementioned operation of the cutoff relay 3 opens the circuit through the wind ings of the subscribers line relay 2. The releaseof relay 2 opens the circuit through the windii'ig of group relay 5 and relay 5 releases unless. a call has been originated by a subscriber on some other line in the group with line 1. The release of relay 5 disconnects the ground at its front contact from starting con ductor 6.

When the calling line is extended, by the operation of relay 55 in theline-finder circuit as hereinbefore described, a ci'rcuitis closed from battery through one of the wind ings of the line relay (not shown) of selector S, over the ring conductor 108, through the right hand winding of polarized relay 91,

lower back contact of relay 92, winding of relay 77, inner lower back contact of relay -89, inner left hand back contact of relay'80,

conductor 72, 'next-to-the-inner upper front contact of relay 55,, inner upper back contact of relay 51, brush 62, over the ring conductor of line 1 and through the calling subscribers. instrument, back over the tip conductor of line 1, brush 61, outer upper back contactof relay 51, next-tothe-outer upper front contact of relay 55, conductor 71, outer left hand backcontact of relay-80, upper back contacts of relays 89 and 92, left hand winding of relay 91 and'tip conductor 107, and through the other winding of the'line relay of selector S, to ground. At the same time that the line relay of the selector and relay 77 a of trunk T are being energized in this circuit, the auxiliary test control relay 80 is being energized in a circuit over conductor 7 4.

through the outer upper front contact of relay 55, to ground at the outer lower front contact of relay 50. The operation of relay 80 does not interfere with the operation of the line relay of selector S andrelay' 77 of trunk T, because the resistance 98 isbridged across tip and ring conductors 107 and 1080f the trunk to the selector before these conduc tors are disconnected from tip and ring conductors 71 and 72 of the trunkto the line} finder. The polarized relay 91 of trunk T is not operated at this time since the current through its windings is not in the proper direction. The ooeration of the line rela of a tor 73 of the lii'ie-findercircuit LF; this groundis effective to hold relay 55 of the line: finder circuit after the slow-t'o-release starting relay O disconnects ground from conductor 7 3, as is hereinbefore described. In operating, relay 94 also connects ground to conductor 95. The test control relay 81 is held operated after relay 5O releases in a circuit from battery through its right hand Winding and inner right hand front contact, outer back contact of relay 79, left hand front contact of relay? 8, conductor 100, right hand back contact of relay 85, conductor 99, outer back contact of relay 90, and over conductor 95 to ground at relay 94. The operation of relay 77 of the trunk circuit T closes a circuit from battery through the left hand winding of relay 78, front contact of relay 77, conductor 100, righthand back contact of relay 85, conductor 99, outer left hand back contact of relay 90, and over conductor 95 to ground at relay 94. Relay 7 8 operates to close the aforementioned circuit forholding relay 81 operated preventing the operation of re lay 79. t

The aforementioned operation of relay 80 is also effective to connect conductor 72 through its inner left hand front contact, outer left hand front contact of relay 81, inner left hand back contact of relay 82, and through the right hand winding of test relay 83 and resistance lamp '96 to the negative pole of the special charging battery 97, and to connect conductor 71 through the outer left hand front contact of relay 8 0, inner left hand front contact of relay 81, outer left hand back contact of relay 82, and through the left hand winding of test relay 83 to the negative pole of the regular central oflice battery. Test relay 83 operates if the line is connected to ground and does not operate if the line is not connected to ground. If the call originated at station W, the current through the winding of polarized relay 11 is ineffective to operate this relay and the identifying ground at contact 15 is not connected to the line, so that test relay 83 does not operate. If the call originated at station J relay 21 is already operated and the current through the test circuit holds this relay so that the identifying ground remains connected fromwcontact 25v through the front contact of relay 21, thence through retard coil 24, resistance 22 and winding 26 of the induction coil to the ring conductor of line 1, and through resistance 23 and transmitter 27 to the tipcond'uctor of line 1; as a result the currents through the windings of test relay '83 are effective to operate the test relay.

8 If the call originated at station M relay 31 is already operated and the current through the test circuit holds this relay operated, so the identifying ground at contact 35 is not connected to the'line and the test relay 83 does not operate. Ifth'e call originated at 1 station R the current through the winding of polarized relay 4:1 is inefiective to operate this relay so that the ground at contact remains connected through the back contact of relay all to retard coil 44, thence through resistance 42 and the winding 46 of the induction coil to the ring conductor of line 1, and through resistance 4C3 and transmitter 47 to the tip conductor of line 1; the currents through the windings of test relay 83 are,

therefore, efiective to operate the test relay.

If relay 83' operates at this time, it closes an obvious circuit through the lower winding of relay 89; relay 89 operates and locks in a circuit through its upper winding and front contact over conductor 95 to ground at relay 94.

WVhen the ground at starting relay 5O is disconnected (by the release of relay 50 as hereinbefore described) from conductors 74 and 7 5, relay releases thereby disconnecting conductors 71 and 7 2 from the windings of the test relay 83 and reconnecting these conductors to the windings of the line relay (not shown) of selector S. If operated, test relay 83 releases but relay 89 holds; if relay 89 is operated the connections between conductors 71 and 7 2 and the windings of the line relay are reversed so that the current over the line '1 is effective to free the line of the identifying ground connection at the i calling station so that this ground will not interfere with the alternate release and reoperation of the selector and connector line relays during the dialing of the number of the called station. Thus, with relay'89 operated, if the call originated at station J relay 21 releases and if the call originated at station R relay 41 operates, in either case to disconnect "the identifying ground. But, with relay 89 not operated, relay 11 remains nonope'rated or relay 31 remains operated '(ac cording to whether the call originated at station 'W or station M) so as to keep the identifying ground disconnected from the conductors of line 1. The polarized relays are slow-to-release so that they hold during transfer from the pulsing relayto the test relay or vice versa.

vVlien thefirst digit of the number of the lo l called station is dialed'rel'ay 77 of the trunk circuit and the line rel ay (not shown) of the selector S are alternately released and reopcrated. The selector switch S is thereby controlled to select a group of trunks each of which terminates at a connector switch having access to the line of the called station. The selector automatically selects an idle trunk which, in the drawing is represented by conductors 156, 157 and 158, terminating at the connector 'C. The selector then disconnects its line relay from tip and ring conductors 107 and 108 of trunk T and extends these conductors through its brushes 153 and 15% to the windings of the line relay (not shown) of the connector circuit C. The re lease of the line relay of the selector discon- I nects the holding ground in the selector circuit from the sleeve conductor 7 3, but the sleeve relay '94 is held operated through brush 155 to ground in the connector-circuit, the closure of this holding ground being caused by the operation of the line relay of the connector circuit as hereinafter described. e

W hen relay 77 of trunk T releases, upon receipt of the first pulse created by the dial ing of the first digit of the called stations number, relay 78 also releases and relay 79 operates in a circuit which may be traced from battery through its winding, right hand back contact of relay 80, back contact of relay 78, to conductor 100 and thence to ground at relay 94 as hereinbefore described. Relay 78 is diiierentially Wound so that it is "fast to'release; and condenser 101 and resistance 102 are so connectedin combination with the winding of relay 78 as to make this relay slow in operating. The condenser 103 and resistance 104: are so connected in combination with the winding of relay 79 as to make relay 79 slow in releasing. As a result relay 77 releases and reoperates in response to each impulse created by the dialing of the first digit, relay 78 releases uponthe first release of relay 77 but does not reoperate until all of the impulses have been received, while relay 79 operates upon the release of relay 78 and holds until after relay 78 has reoperated. The operation of relay 79 causes the release of relay 81. i

During the interval between the reoperation of relay 78 and the opening of the contacts or" slow-to-release relay 7 9 a second test of the calling line is made to further identify i the calling station. With relay 79 operated the reoperationof relay? 8 closes a circuit for operating control relay 80, from battery through the Winding of relay 80,*front contact of relay 79, left hand front contact of relay 7 8, to conductor 100' and thence to 7 ground at relay 94 as hereinbefore described.

In operating, relay 80 opens the circuit through the Winding of relay 79 and as soon as relay 79 releases the circuit through the winding of relay 80 is opened and relay 80 releases. While relay 80 is operated conductors 71 and 72 are connected through the back contacts of relays 81' and to the windings of the test relay 83, and resistance 98 is bridged across conductors '107and 108'to opcrate the line relay of connector C. The windings of the test relay having been re versed at the'contacts of relay 81 with respect to the tip and ring conductors of the calling line the current over the line is in the opposite direction to the current on the preceding test. If the calloriginated at station V7 relay 11 operates thereby connecting the ground at contact 15 to the retard coil 14, thence through resistance 12'and winding 16 of the induction coil to the tip conductor of theline and through resistance 13' and transniitter 17 to the ring conductor'of the line; this results in the operation of test relay'83. If the call originatedat station J relay 21 does not operate so that the identifying ground connection is not closed and test relay 83 does not operate, H the'call originated at station M relay 31 releases thereby con-.

necting the ground at contact 35 through rethe left hand winding of relay 88; relay 88 looks through its right handwinding and front contact, over conductor 95110 ground at relay 94, it operated relay 83 releases when relay releases. The release of relay 79 closes a circuit for operating relay 82, this circuit may be traced from battery through the winding and right hand back contact of relay 82, inner right hand back contact of relay 81, outer back contact of relay 79, left hand front contact of relay 78, to conductor 100, and thence to ground at relay 94:. Re-' lay 82 looks through its inner right'hand front contact, conductor 99 and the outer back contact of relay to the same ground. v Vith relay 80 released the connection over conductors 71' and 72 from the calling line is extended over conductors 107 and 108 and through selector brushes 153 and 154: and Con ductors 156 and157, to the windings of the line relay (not shown of connector C. When the calling subscriber dials the remaining digits of the called stations number the connector switch is effective, in the usual man-' ner, to make connectionwith the terminals to which the line 200 oi the called station D is connected.

During the dialing ofthe second digit, re

lays 77, 7 8 and 79 of the trunkcircuit T function in the same manner as during the dialing of the hrst'dlgit. The reoperation of relay 78, after all of the pulses created by the dial ing of the second digit, again closes aacircuit for operating control relay 80 as hereinbefore described. Relay 80 connects conductors. 71

and 72 through its front contacts, the back the left-hand back contact of relay 85, outer I right-hand front contact of relay 82, to the right-hand front contact of relay 80,'and

' thence to ground as traced for operating relay 8'0. Relay 85 locks through its inner lefthand front contact, conductor 99, outer back contact of relay 90, over conductor 95 to ground at relay 94;. Until relay 7 9 releases, the circuit through the winding of relay is now traced through the outer right-hand front contact of relay instead of through the front contact of relay 78 and the right-hand back contact of relay 85. Relay 85 connects battery through its outer lefthand front contact to the windings of test relay 84 thus completing the circuit for testing the calling line. Since the same potential is connected to both sides of the line the polarized relay 11 remains normal if the call originated at station V1 the polarized relay 21freleases if the call originated at station J, the polarized relay 31 remains normal if the call originated at station M,, and the polarized relay 411 releases if the call originated at station R. Relay 84 is, therefore. operated if the call originated at either of stations M or R, the identifying ground connection being closed; but relay 841 does not operate if the call originated at either of station's 1V or J, the identifying ground connection being open. If relay 84 operates it closes an obvious circuit for operating relay 86; and relay 86 looks through its inner lefthand front contact, over conductor to ground at relay 94. As soon as relay 79 again releases relay 80rele'ases thereby closing the connection between the calling line and the connector so that the dialing of the third digit of the called number is effective to control the operation of the connector switch. \Vith relay 85 operated the winding of relay 7 7 is short-circuited so that relays 7 7 and 78 release; and relay 77 is not included in the dialing circuit.

Assume that the line of the called station is found idle, that ringing potential is Jonnected to this line and that the subscriber at the called station answers the call. When the subscriber answers, the connector circuit reverses the connections between the windings of the line relay and the tip and ring conductors of the calling line so that the current through the windings of the polarized superisory relay 91 of trunk T is effective to operate. this relay. Relay 91 closes the circuit for operating reversing relay 92. 7 Relay 92, in operating, reverses the connection from the calling line over conductors 71 and 72 with I'BipGClZ to conductors 107 and 108 so that the current through the polarized relay at the calling station continues in the direction which prevents the closing of the ii'lent'ifying ground connection. If the identifying ground connection were closed during conversation the quality of the transmission would be affected.

In operating, relay 92 also, connects ground to the righthand winding of relay 93 and connects interrupter 133 (shown in Fig. 3) over conductor 105, through the outer upper front contact of relay 92, m ddle back contact of relay 90, left-hand winding 01' lay '93-, conductor 113', back contacts of relays 131 and 132, winding of alarm relay 129, right-hand back contact of relay 150, and through the back contact of relay to battery. Assume that the common register control circuit RC is not in use. Interrupter 133 alternately closes and opens a connection to ground; the closed periods have a duration of approximately one-quarter of a second and the open periods a duration of approximately two seconds. With the interrupter brush connected to ground, or as soon as it is so connected, relay 93 of trunk T and alarm relay 129 of the register control circuit operate. in operating, relay 93 disconnects conductor 139 from conductor 106 and closes a circuit from ground at the outer lower front contact of relay 92, right-hand winding and front contact of relay 93, over conductor 130, winding of relay 131, to battery at the back contact of relay 1415. Relay 93 locks and relay 131 operates in this circuit. By disconne ting conductor 130 from conductor 106 no other of the trunks to which the control circuit RC is common can make use of the control circuit until relay 93 releases. Relay 131 closes an obvious circuit for operating relay 132and opens the circuit through the lefthand winding of relay 93 and the winding of relay 129 so as to release relay 129. Should relay 131 fail to operate relay 129 remains operated and the ground connected through its front contact to conductor 151 is effective to operate an alar I In operating, relay 132 connects ground to alarm lead 151, and connects the windings of counting relays 134 and to interrupter 133. As soon as interrupter 133 closes the circuit through its winding relay 134 operates, thereby connecting the winding of relay 135 through the right-hand front contact of relay 13 1 to ground at relay 131. As long as the ground connection atinterrup'er 133 is closed the winding of relay 135 is short circuited but as soon as this ground is opened relay 135 operates in series with the winding of relay 134.- to the ground at relay 131; relay 13 1 is locked in this circuit. In operating, relay 135 transfers the connection from interrupter 133 to the winding of relay 136 and when the ground connection is again closed at interrupter 133 relay 136 operates. Relay 136 looks through its righbhand front contact to the ground at relay 131. Relay 136 closes a circuit for operating relay 99 of the trunk T; this circuit may be traced from ground through the inner left-hand front contact of relay 13.6, conductor 111, outer lefthand front contact of relay 93 of trunk T, conductor 110, and through the inner lefthand back Contact and winding of relay 90 v to release relay 85 but the winding of relay to battery. .Relay 90 locks through itsinner left-hand front contact over'conductor 95 to ground at relay 94. In operating,relay'93 disconnectsthe' sleeve conductor 73 of the line-finder LF from the ground at .relay 94 and connects conductor 7 3:, through the inner left-hand front contact ofrelay 93, over conductor 112, to ground at the right-hand back contact of relay 139 of the register control circuit RC. The line-finder relay 55 and the cut-off relay 3 ofline 1 are thus held operated under control of relay 139 to prevent the release of the connection until the message register of the calling station has been operated. The operation of relay 90 is effective 77 remains short-circuited by the outer righthand front contacts of relay 90after relay 85 'has released. Relay 90 also opens the con nection between the left-hand winding of relay 93 and interrupter 133, and connects the ground at relay. 136 of the register con trol circuit BO overconductor 111, through the outer left-hand front contact of relay 93, conductor 110, and. through the inner right- I hand front contactof relay 90 and through V the contacts of relays 89, 88 and 86 to the winding of one of relays 117 119, 121 and 123 according to whether relays 89, 88 and 86 are normal or operated." If the call originated .at station Wrelays 86 and'89 are norinal'and relay 88yis operated so that relay 11 71operates; if the, call originated at station'J- relays 86and 88 are normal and relay 89 isjoperated so that re1ay-119operates; if the call originated'at station-M relay 89 is normal and relays 86 and 88 are operated so that relay 121 operates; and if the calloriginate'd at 1 station R relay 88 is normal and relays 86 and 89 are operated so that relay 123 operates. If relay 117 operates it closes a circuit for operating relay 118 and relay 118 connects the winding of message register 125 to the sleeve conductor 4 of the line lin parallel with the --winding of the cut-off relay 3; if relay 119 operates it closes a circuit for operating relay5120 andrelay 120 connects the winding of message register 126 to conductor 4 -if relay 121 operates it closes a circuit'for operating relay 122 and relay 122 connects the winding of message register 127 to conductor 4;

and if relay123 operates it closes a circuit for operating relay- 124 and relay 124 connects the winding of messagegregister 128 to conductor 4. The operation of any one of relays 118, 120, 122 and 124 is also effective to connect ground to conductor 140.

The aforementioned operation of relay 136 was also effective to connect interrupter 137 through its outer left-hand front contact and .the left-hand back contact of relay 139fto the windingsof relays138 and 139. Interrupter 137 alternately closes a connection to ground for three-tenths of a second and opens the connection for two-tenthsof a second; As

soon after the operation of relay 136, as-the ground: connection is closed at interrupter 137, relay138 operates. Relay 138 closes a circuit from battery through the windings of relays 13,8 and 139 in series and through the left-han-dfront contacts of relays 138 and 134 and over conductor 140, to ground at one of relays 118, 120, 122 and 124 which has been operated as hereinbefore described. The

winding of relay-1391s short-circuited until the ground connection atinterrupter 137 is opened at which time relay 139 operates-and with relay-138 is locked in,;the circuiti to ground over conductor 140.: The operation of relay 139 disconnectsjconductor 112 from the ground at its right-hand back contact and connects this conductor through its righthand front contact, resistance 144, and

through lamp 143 to'booster battery 142," thereby-holding the cut-off relay 3 and operating the message register of the calling station. I Th-e'operation of relay 139 is'also eifective to transfer'the connection from interrupter 137 from the windings of relays 138 and139'through the leftehand front con tact "of relay 1139' and left-hand back contact of relay 150 to the winding of relay .145. As soon thereafter as the ground connection at interrupter 137 is again closed relay145- operates; Relay 145 locks through its front contactto ground on conductor 140; In op- I crating relay 145 opens the'circuitthrough the windingof relay 131 and through the locking winding of relay 93 thus causing the releaseof. these relaysj The release of relay 131 causes the release ofrelays 132,134, 135

and 136. The release of relay 132 opensthe connection to interrupter 133 to prevent the reoperation of relay 134" and disconnects ground from alarm conductor 151. The release of relay 134 causes the release of relays i 138 and 139. The release of relay 136 disconnects ground from conductor 111 thereby'releasing whichever twoof relays 117, 118, 119,

120, 121, 122, 123 and'l24 were operated; the.

release of relay 136 also opens the connection tointerrupter 137 to prevent'the reoperation of relay 1,38. The release of relay 139 disconnects the booster battery 142 from conductor 112 and reconnects this conductor to ground. The release of relay 93 reconnects the sleeve conductor 73 to ground at-relay 94 to hold relay 55 of the line-finder circuit and the cutoff relay 3 of the line 1 until the connection is released. The release ofthe register control relay 118, 120,122 or 124 disconnectsground supervisory relay 91fand the line relay (not shown) of connector' 'circuit 0 release. The

:release offthe linewrelayof the connector is returns to normal inthe usual manner.

ZWit'h the holding'ground opened in the con- 3 o .7 at theconnector-and the releaseot relay 94 1 disconnects ground from sleeve conductor 73 1 thereby causing the release of line-finder relay55 andcut-ofi relay 3. The release of re- -lay 55 closes acircuit for operating the release-magnet 58-ot.the:line-finder LF and the iilinefinder .switch is returned to -normal. UWhen theswitch vreaches normahthe VON springs are returned to their normal position i-thus; opening the circuit through the lower goz-winding of relay 53. Relay 53 -releases unm wlind-ing until ground vis. disconnected from ygthis conductor.

some manner other than by the proper-closure "of the identifying ground connection at the I. callingstation .test relay 83 would operate 1 is effective to operate relay- 87 instead of operating one of relays 117 119; 121-and-123. V

The=circuitfor operating -relay 87 -may be traced -f-rom battery-through theleft-hand windingof relay 87 thence through the inner iront contact of relay188- and'the outer flower 40' :front contact of relay 89, -inne1- right-hand 'Ffront contact of relay 90, conductor 110, outer 1 -edthrough brushes 153 and 154k ofselector S and through the inner back contacts of :relay -l68 to the-winding of relay 165. iTheloperleft-hand front contact of relay 93, conductor 111, to ground at relay 136. Oiiif there Were a failure of the i'dentityingground at the calllfi ing station neither of r'elays 88-and 89 would be operated and 'the circuit for operating relay '87- would be tracedthrough the back contacts of relays 88 and 89 to the ground at relay 136. Relay87 connectsground over con- 'ductor 115- to the winding of register 1 16. 'Register 146 records the existence of a trouble cOnditiOn and since none of relays 117, 119, 1'21-and 123 were operated, the register control circuit completes its cycle of operations 1 without operating any of the message regisusual manner.

If-the number of failures recorded by register ltfi'warrantskey 152 may be operated/to l m; prevent; therelease I of the calling line although theselector and connectoncircuitsare 7, returned-to 1 normal in the usual manner.

.,With key 152 operated relay 87 locks inia cir- (one of relays 117,"119, 121 and l23zoperatelbut; bless the startingconductor-6J5 grounded in :which caserelay 53 holds through'its upper i If thevline 1 .:Were' connected to ground in I registercontrol ci-rcuitItO.

-, key 152. In this case the release mag-netlof efi'ectivei to disconnect ground: trom sleeve conductor 158 and whenthe called subscriber rhangsup thereceiver the connectorrswitch line-finder LFca-nnot. operate since :its circuit is held open at the left hand contact-:oflrelay With relay- 87 operated ground is connected to conductor 95 to preventtherelease of the relays which hold over this conductoriwhen relay 94 disconnects ground therefrom: and

, ground islalso connected over conductor; 11 1 to operate alarm relay 147 of the register controlcircuit. .zIn operating, relafil l'liclosesthe circuit for lighting lamp 148 and connects ground to conductor 149 to operate an alarm.

Should relay; 1'32 .failto operate after" relay '129has-operated,v or relay? :132 fails. to

7' release; aft-er. its operationy 1 the ground"-;con nected to, :lead' 151 is effective- .tozoperate. an alarm. :I'f relay 134 fails to operate,:theoper- '2I. \]lO l of anyrof relays 118,120,1122and 124:

closes acircuit' foroperat-ing relay 150 ;';or.if

the corresponding-one of relays 118; .1 20, 1-22 and 12 1 fails ,tooperate1a= circuit :is closed,

1-11; a connection-is establishedbietweenrthe "calling subscribers station and-avcalledrstation for; which, nocharge should :beunadeg the :omthe :firstandalso on thesecorldtest-of the 30 line. -Relays 89 and 88 -would therefore both i; be operated and, ifthe-connection is completi i @ed and the called subscriberanswers, the-op- :erationof relay 90 as hereinbefore'described a -relay-does notcoperate; :In this case the connection is released: without amakingiuseofvthe If the calling: subscriber dials; a; number which consists; of only one {digit :to 1 establish o connection: Wl'lillfll'l' operator thecalling line is extended through :;:the line,fin,der 1: L'F, trunk Z T,1 selectorHS :a-ndqoverrthe trunk OT to theopera-tors; position at ,O. rllhe rliDewIG- 4 lay 165 of: the trunk OT' operates when they connection tromthezcalling station is, extendation-ofwrelay 165 causes the operation -10f,- slow-to-release; relayj166. :Relay 5166 :con-

7 nects. a busy and holdingground throughsits left-hand contact; over- CODClLlCbOIIlGl and throughybrush 155 'tQ'itlle sleeve conductor 109 of selector ;Sv so as; to hold relayfi ottrunk r, T,operated. The ground atv thenlft-hand contact of relay166isv also connected through the backcontactgot relayi168to'thezwinchng of relay 167. i Relay; 167;=opera= tes therebyzdisconnectingthe tipand ringzconducto'rs 170 s utters; andzthe .connection is released in the f and, 171 from; the;springs- :of'j ackf 172.;and closes a circuit forj..lighting1:ltine; lampr169.

connectionfl'QIn the cazlljing line '1 from; the win ings of: relay 165 :to; conductors; .170 and 171. :Relay-1'68rin operating; alsoaopensfthecircuitthro-ugh thewinding:of--relay 167; and con- I :nects ground through; its: outer uppergfront w contacts to the winding of relay 166 so as to prevent the release of relay 166, Relay 167 is slow in releasing so that the circuit from the calling line through the line-finder LF, trunk T, selector S and trunk OT is opened long enough to release relay 77 in trunk T before the conductors 170 and 171 are extended through the back contacts of relay 167,

springs of jack 172 and through the tip and ring of plug 173 to the windings of relay 174. Relay 77 of trunk T reoperates and relay 1741 of the operators cord circuit operates as soon as conductors 170 and 171 are thus extended. The release and reoperation of relay 77 of trunk, T simulates the dialing of a second digit and is effective as hereinbefore described to cause thetest relay 841 to be connected to the calling line for completing the identification of the calling station. If the call is a free call, relay 91 of trunk T is not operated and no use is made of register control circuit RC. But, if the call as completed through the operators. cord circuit is one for which a charge should be made, the reversal of the windings of relay 174 with respect to conductors 170 and 171 causes the operation of relay 91; the register control circuit is then effective to operate the message register of the calling station as hereinbefore described. I a

The invention is not limited in its application to the system herein disclosed, but is applicable to any automatic, or semiautomatic: telephone system whichis arranged for party line message rate service and in which the automatic switching mechanisms are directly controlled by the calling subscriber.

What is claimed is:

1. In a telephone system, a line, a plurality of subscribers stations permanentlyconnect' ed to said hne, means at each of said stations for distinguishing it from the others, a dial, at each station, means including a trunk for.

extending said line when a call is originated at any of said statlons, and means lndlvidual to said trunk for preventing said distinguishing connection, and means for automatically controlling said identifying connection so as to prevent this connection from interfering with the transmission of dial impulses and;

from impairing the transmission of speech.

3. In a telephone system, a line having a plurality of subscribers stations one of which is a calling station, an identifying connection at each of said stations, means at each of said stations for controlling the identifying connection, an impulse sender at said calling station, means including a trunk for extending said line, and means associated with said trunk and cooperating with said controlling means to free said line of said identifying connectionduring 'thetime that said impulse sender is being operated.

' 4. In a telephone system, a plurality of 'subscribers"1stat1ons one of which is a calling station, a message register for each of said stations, a called station,

trunks-, means including one of said trunks for extending said line to said called station,

line having a means for selectively operating the message register of said calling station, and means common to all of said trunks for delaying the operation ofthe message register of said calling station. w 1 L 5. In a telephone system, a line, a plurality of subscribers stations permanently from the others, a deviceat each of said stati'ons for creating impulses, a trunk,'means for connecting saidlineand said trunkwhen acall is originated at'ione of said' stations,

testing means-effective as soon assaid line is connected to said'trunk for partially ldontifying the calling? one of: saidstations, means associated w th sald trunk for ireceiving impulses, meanseffectlve as soon as a set of impulses has been-received to'check said partial identification, and meanseffectiveas s oon as another setof impulses has been received to complete the identification of the calling one: of said stations. 1

6. In a. telephone system, a line,a plurality of' subscribers stations permanently.

connected to said line, a ground connection and a polarized relayzfor controlling said ground connection at each station, an impulse sender at each station, a'trunk, a selector associated with said trunk, means.

effective upon the origination of aicall at any of said stations to extendsaid line to said trunk, means for testing s aid line to partially identify the calling one 'o fss'aid stations,'means dependent upon the presence of a ground connection at said calling station for reversing theconductors of said line with respect to said selector, means rendered effective by the transmission of a train of" impulses created by the operation of said connected to said line, means at said stations for rendering each of them-distinguishable impulse sender for testing said line a second time, and means for testing said line a third time to complete the identification of said calling stations.

7. In a telephone system, a line having a' plurality of subscribers stations one of which is a calling station, a ground connection and'means for controlling said connectlon at each station, a dial at said calling station, trunks, a. selector, a called station, a

nmeansjncluding. one of; said trunks and-said ws'elector for establ-ishing a connection between said hailing andrsaid called stations,

means for testing said :line 7 to partially iden- 1 :tify said callingstatiom- 2means dependent upon the; PBQSGIICG Of a; ground connection at the! time :of said test for reversing theiconductor :ofvsaid line-=:With==respect to said 4S8- leotor so that saidlinowill notpbe connected x top-ground 'cluring ;dialing,7:means for comwpletingthe"identification. ofsaid callingrstav ytiong aa'egister individualtogsaidcaillingstatiom .charging means common ;to allof-" said :tztmnks and rendered effective, :by the; answer 16 1500152 :the w subscriber at; the i called station: for

pperating; said .register,-;- means common to zassaid trunkszfor delaying the operationof 1 shid register,- andsmeans for freeing-said line 3 mi said;- identifying ground connection dur- 0 ing conversation.

' v8.1:Ina telepho11esystem; a line having a pluralityv of :"s'ubscribe-rs "stations one of whioh is a callingastationgardial atsaid callv iingxstation means at eachofqsaid: stations zsnfor: distinguishing-it from :theothers means lzfOI. testing said: line tog partially: iidentify s-aaidv calling -yst2tti011, an automatic switch 1 (selective-1y v'controlled by zithe :operation of maid dial; means: :for simulating; the: dialing BOUOfilfillt additional i'digit, and :means' rendered z efiectiveiby: said simulation: for completing a the: identification offisaid balling;- station.

;:a9. In. a telephone system; aw-line having a plurality of subscribers 3Stati0I1S 30118 of w-Which is callingstatiom a dial: at said call- :ing ;s,tation,-?meansnat each i of: said-- stations 412501 3 distinguishing :it from "the mothers, a called station-whose number consists of only :aonerdigit; meansifor establishing a-" c0nnec i q ution between: :said; calling and saidl called .sta-

:ttions,i:meanss effective ,before the number of wsaid zcalled -"station is a dialed .for; partially :ridentifying. said calling; station, means efi' festive immediately: after "the number 'of said i'wlled station is 'dialedvfor-checking saidpartial identification; means for simulating the idialingof. another digit andrm eans rendered F- effective by" said w'simulation' for" completing the identificationv 'ofsaid calling station. '50 '5 I-nxwitness iwhereofl. I: hereunto subscribe :-;my;-name this 27th.-'daya=ofiJ 11116,'T1929.

RAY L. :"ESTQKELY. 

